In a Business Writing workshop I learned about Gunning Fog Index.
Fog Index measures the readability of English writing.
Which made me wonder if this can help me with other writing projects.

What is the ideal Fog Index?

That would depend on how well your audience can read.
An index of 12 or more is for people with a reading ability at the University level. This would be ideal for an academic paper.

If you're looking to reach a wider audience, a lower index number would be more appropriate. For the general population an index of 8-10 is ideal.

Different publications have a different fog index:

Reader's Digest 8-9

Time and Wall Street Journal 11

The Bible and Mark Twain 6

Calculating the Fog Index

Select a section of writing about 100 words in length. End with a complete sentence.

Count the number of sentences in that section

Count the complex words in that section. Complex words have three syllables or more. Do not include proper names or compound words. Do not include suffixes as a syllable (e.g. ing, ed and es)

Divide 100 by the number of sentences. Add the number of complex words.

Multiply this number by 0.4 for the Fog Index number.

And, for those of you who like equations: 0.4(100/b +c) = Fog Index

Online Fog Index Calculators

If you are having difficulty with the calculation, you can always use an online calculator. I've noticed they give different results plus they can't take out proper names and so on, but they will giver you a general idea.